The present invention relates to a method of fabricating an instrument panel, particularly to a method of fabricating an instrument panel where previously and separately formed panel core material and skin are arranged and held in a pair of dies of a mold and a foaming material of polyurethane or the like, injected between the panel core material and the skin, is foamed whereby the panel core material, the skin and a foamed layer are integrated.
Conventionally, a skin of this kind of instrument panel is formed using a thin flexible material of a plastic sheet or the like. Therefore, when an end edge portion of the skin is simply bent to the rear side a side face portion thereof is formed projecting, the projected side face portion is deficient of self standing performance and falls toward the inside by its own weight. When such a skin having the projected side face portion is used, if the skin is arranged inside of a die of a mold, falling of the projected side face portion produces a gap between the projected side face portion and a peripheral wall of a recess of the panel core material arranged and held in the other die and the sealing performance therebetween is much deteriorated. Therefore, the foaming material leaks or wrinkles or the like is caused at the end edge portion of the skin whereby the product yield is reduced due to deterioration of appearance or the like.
As a measure for preventing leakage of foaming material or deterioration of outlook caused by falling such a projected side face portion, conventionally, as disclosed in JP-A-07314469, a recess groove is formed by folding back outwardly a projected front end of a side face portion formed by bending an end edge of a skin rearwardly, and a member for holding the edge portion of the skin projected from one die is fitted to the recess groove. Thus, the skin is positioned by holding the projected side face portion of the skin and preventing the projected side face portion from falling inwardly (hereinafter, referred to as prior art).
However, according to the prior art, the front end of the side face portion projected by bending the end edge portion of the skin rearwardly, must be folded back outwardly to form the recess groove and accordingly, the shape of the skin per se is complicated and an increase in molding cost is inevitable.
Further, it is very difficult to set a timing for drawing out the member, holding the edge portion of the skin fitted to the recess groove at the front end of the projected side face portion, from the recess groove, and pulling and incorporating the member into one die of the mold. That is, basically, when the member for holding the edge portion of the skin is pulled and withdrawn into one die in the midst of foaming a foaming material injected between the recess portion of the panel core material and the skin, thereafter, the projected side face portion is pressed toward the inner face side of the peripheral wall portion of the recess of the panel core material by a foaming pressure and accordingly, the projected side face portion can be prevented from falling inwardly. However, a timing of generating the foaming pressure sufficient for preventing the projected side face portion from falling is dispersed depending on kind of foaming material, magnitude of a cavity or the like. Therefore, the member for holding the edge portion of the skin may be pulled and withdrawn into the die before generating the foaming pressure sufficient for preventing the projected side face portion from falling. As a result, a portion of the projected side face portion may fall inwardly by which the sealing performance may be deteriorated. Or, the member for holding the edge portion of the skin may be forcibly pulled and withdrawn into the die at a stage where the foaming pressure is intensified excessively. As a result, during the pulling operation, the projected side face portion, particularly, its base end portion may be impaired or wrinkled or the like by which the appearance may be deteriorated.
Further, in the above-described prior art, the recess groove is formed by folding back outwardly the front edge of the side face portion. Therefore, the side face portion of the skin is provided with inner and outer double folding structure and a slight gap may be caused at a boundary between the inner face of the peripheral wall portion of the recess of the panel core material and the side face portion of the skin. After finishing, dust and dirt or the like may enter between the gap during use which is not preferable for appearances.